Methods and devices are provided for mixing two or more powders together. In one exemplary embodiment, an additive, for example, silica particles, is added to toner so as to improve the flowability of the toner. The methods and devices, however, are applicable to various types of powders, for example, powders which are combined in preparing food items and in preparing pharmaceuticals.
Dry particles that form a powder, such as dry toner particles, typically are mixed with another material, such as an additive. This is accomplished for various reasons, such as to enhance flow, i.e., a powder made up of both toner and an appropriate additive such as silica may exhibit enhanced flow characteristics.
Toner can be mixed with an additive via many processes. For example, in an emulsion/aggregation chemical toner process, toner provided in a wet-cake form is dried. The drying process can be accomplished by using a torroidal air dryer, for example. The dried toner can then be stored in a collection area. The dried toner, however, tends to become compacted in the collection area because the toner particles have strong cohesive forces. Thus, it is desirable to mix an additive, such as silica, with the toner particles so that the dried toner is easier to handle in subsequent processes.
For example, the additive can be mixed into the dried toner in the collection area. This requires a mixing device to perform the mixing in the collection area, which increases the cost and complicates the process. Another technique would be to add the additive to the toner when it is in its wet-cake form. The additive theoretically would mix with the toner particles during the drying process.